This invention relates to a picture signal binarization system for binarizing analog picture signals.
Conventionally, a multiple-tone image such as a photograph is converted to picture signals by a dither method, while a two-tone image, such as a character is converted to picture signals of two gray levels.
The actual image on a document may be, however, the mixture of an image portion, which should be converted to picture signal of multiple gray levels as a photograph is, and an image portion which should be converted to picture signals of two gray levels, as a character is. If such an image is processed by the dither method, a character portion may be illegible. Further, if it is converted to picture signals of two gray levels, a multiple-tone image portion cannot be reproduced.